This invention relates to a sliding body, particularly one of ceramic material, used for sliding systems, particularly for sliding ring-type seals.
Axial and radial sliding ring-type seals serve as a rule for sealing rotational machine parts against fluids (liquids or gaseous media), and in most instances consist of a stationary ring and a rotating sliding ring, these being pressed together by means of a spring element. These sliding rings from a seal gap in which the sliding surfaces of the sliding rings are arranged opposite to each other. When the seal is in operation there is a liquid sealing medium in the seal ring and this is under a pressure difference.
It is possible, for example, to use axial sliding ring-type seals that ensure a hydrostatic-hydrodynamic seal in difficult applications. The pressure of the check and lubricating liquids is controlled by virtue of a suitable arrangement so that the sealing is relieved hydrostatically and can become operative even in the event of a high internal pressure. In addition, so called hydrodynamic enhancement depressions are provided at least in the surface of a sliding face of the slide rings (DE-AS 14 75 621). In known depressions this involves blind drillings of equal depth and equal diameter, arranged equidistantly along a circle and which work together with open-rim grooves. These depressions are intended to ensure lubricant dispersal since a hydrodynamic lubricant and carrier effect is stopped. The non-optimal effect of these known depressions is improved in accordance with DE-PS 29 28 504 by the fact that the individual hydrodynamic enhancement depressions are of alternating depths at a depth periodicity that increases and decreases periodically along the circumference. Such an arrangement can only be effected at considerable cost and providing non-brittle materials are used since the production of depressions of this kind in brittle materials is practically impossible. Furthermore, like all other familiar arrangements, the familiar arrangement cannot be adapted to changing loads that may occur during the operation of a sliding ring-type seal.
A sliding ring-type seal should have good emergency running characteristics and be resistant to aggressive fluids. In addition, it must be able to withstand the temperatures that may occur during operation.
Special measures to cool the sliding rings will be necessary in the event of high pressures and temperatures. In this connection, it is an already familiar fact that cooling medium channels can be provided in the sliding ring bodies, these being capable of conducting a cooling medium (Swiss patent 413 522). However, it is extremely difficult and costly to incorporate such channels and, in particular, is possible only at extremely great cost in the case of ceramic materials.